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3.4 Translating and Setting Page Table Entries

This set of functions and macros deal with the mapping of addresses and pages to PTEs and the setting of the individual entries.

The macro mk_pte() takes a struct page and protection bits and combines them together to form the pte_t that needs to be inserted into the page table. A similar macro mk_pte_phys() exists, which takes a physical page address as a parameter.

The macro pte_page() returns the struct page, which corresponds to the PTE entry. pmd_page() returns the struct page containing the set of PTEs.

The macro set_pte() takes a pte_t such as that returned by mk_pte() and places it within the process's page table. pte_clear() is the reverse operation. An additional function is provided called ptep_get_and_clear(), which clears an entry from the process page table and returns the pte_t. This is important when some modification needs to be made to either the PTE protection or the struct page itself.

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